I believe that there'll be an MLS1 and MLS2, with pro/rel in between.
Also, I believe that USL will have 3 divs. with MLS reserve sides involved still.
I think that will happen eventually, but it will be a hard sell in the near future...'what do you mean my team might be in the 2nd division in a couple of years? I just paid a $200 million franchise fee!'